What is the function of a relay in HVAC applications?

A relay in HVAC applications serves the crucial function of controlling a high-power circuit with a low-power signal. This is particularly significant because many components within HVAC systems, such as compressors, fans, or heaters, require a substantial amount of electrical current to operate. However, controlling these high-power devices typically involves using low-power signals, which can originate from thermostats or control systems that operate at much lower voltage levels.

When a low-power signal is applied to the coil of the relay, it generates a magnetic field. This magnetic field then closes or opens the contacts within the relay, allowing or interrupting the flow of electrical current to the high-power circuit. This mechanism provides a safe and effective way to operate larger devices without the need for the control systems to handle high voltage or high current directly.

This arrangement maximizes safety and efficiency within the HVAC system, as the sensitive control electronics can function without the risk associated with high-power circuits.